«4 
Caffeine  and  Theine. 
Am.  Jour.  Pharn.. 
Feb.,  1893. 
molecular  proportions  of  water,  and  the  anhydrous  salts  melted  at 
the  same  temperature,  viz.,  248-5°  (corr.).  The  analytical  data  cor- 
responded with  the  formulae  given  above.  The  complete  corre- 
spondence in  the  properties  and  composition  of  the  aurochlorides  is 
satisfactory  evidence  of  the  absence  of  a  structural  difference  in  the 
bases.  In  order  to  further  confirm  the  identity  of  the  two  sub- 
stances, a  specimen  of  each  was  converted  into  the  mercuric  chloride 
compound  (C8H10N4O2,HgCl2),  a  stable  crystalline  salt.  Both  pre- 
parations were  found  to  melt  at  the  same  temperature,  viz.,  2460 
(corr.),  and  to  exactly  correspond  with  each  other  in  other  respects. 
The  complete  identity  of  caffeine  and  theine  having  thus  been 
demonstrated,  the  observed  differences  in  their  physiological  action 
must  be  ascribed  either  to  impurities  in  the  specimens  used,  or 
to  variations  in  the  animals  employed  in  the  experiments.  The 
circumstance  that  theine  was  found  to  be  more  active  than  caffeine, 
and  to  be  capable  of  producing  effects  not  produced  by  caffeine, 
tends  to  support  the  view  that  the  theine  was  impure.  It  is  now 
well  known  that  tea  contains  other  bases  than  caffeine,  the  presence 
of  traces  of  which  might  be  sufficient  to  account  for  the  observed 
differences. 
During  the  preparation  of  the  pure  aurochlorides  for  a  compari- 
son of  their  properties,  the  authors  obtained  two  new  and  interest- 
ing auric  derivatives  of  caffeine. 
When  an  aqueous  solution  of  caffeine  aurochloride  is  heated, 
a  yellow,  flocculent  precipitate  is  gradually  formed,  which  is  insolu- 
ble in  alcohol,  chloroform,  and  ether,  but  dissolves  in  hydrochloric 
acid,  reproducing  the  aurochloride.  The  substance  dried  at  iOOD 
forms  a  pale  yellow,  amorphous  powder,  which  melts  at  207°  (corr.). 
Analysis  proved  it  to  be  aurochlor  caffeine  CSH9  (AuCl2)N402,  a  sub- 
stance in  which  one  atom  of  hydrogen  in  caffeine  is  replaced  by  the 
group  (AuCl2).  It  is  pointed  out  that  the  ready  formation  of  this 
remarkable  compound  from  caffeine  aurochloride  by  the  loss  of  two 
molecular  proportions  of  hydrochloric  acid — C8H10N4O2,HCl,AuCl3 
=  2  HC1  +  C8H9(AuCl2)  N402 — is  better  shown  by  Medicus'  formula 
for  caffeine  than  by  that  proposed  by  Emil  Fischer ;  since  in 
Medicus'  formula  the  CH  group  which  loses  hydrogen  is  repre- 
sented as  contiguous  to  the  doubly  linked  nitrogen  atom,  to  which 
the  auric  chloride  is  attached. 
By  the  reaction  of  an  alcoholic  solution  of  potassium  diloraurate 
